After distillation, the new spirit is casked and moved to a warehouse where, depending on its intended use, it may age for a period of a few years to several decades. Generally speaking, cognac is aged in barrels made from oak from either the Tronçais or Limousine forests.

The eau de vie is aged in a combination of new and older casks. Typically, new casks are used for six months to two years. The spirit is then transferred to older casks of either intermediate age, one to three years or three to eight years, or even older casks whose wood is more neutral and exerts less influence on the maturing spirit.

The combination of casks used and their relative age depends on the producer, and is another aspect of a cognac house’s style. VS cognacs almost always get some exposure to new oak while Remy’s Louis XIII is only aged in older barrels of neutral wood.

Limousine oak has a coarser, wider grain than Tronçais oak. A coarser grain allows more tannins and flavouring compounds to be extracted from the wood. It also allows more oxygen to pass through the barrel, resulting in more oxidation and a faster maturity. Limousine oak is used for cognacs intended for bottling at a younger age.

Tronçais oak has a tighter, finer grain. It has less extraction and less oxidation. It’s used for cognacs that are intended for extended aging. A cognac subjected to extended aging in a cask of Limousine oak could extract so much tannin that it would probably be undrinkable.

In recent years, several cognac houses have experimented with maturing eau de vie in barrels that previously held other liquids. Martell, for example, released Blue Swift, a VSOP cognac that was finished in ex-bourbon barrels. Technically this can’t be identified as a cognac, however, and is instead labeled as an eau de vie de vin.

Courvoisier recently launched a PX sherry-cask-finished cognac. Under appellation rules, spirit matured in casks that previously held wines or wine-based spirit can still be called cognac.

A second consideration is the relative humidity of the warehouse in which the cognac is aged. Traditionally, cognac warehouses were built along the Charente to facilitate transport. Being adjacent to the river, these warehouses had a higher relative humidity, 90 to 100 per cent. Those warehouses built farther away from the Charente were dryer and had less humidity, 40 to 60 per cent.

A barrel of cognac from Grand Champagne distilled in 1948 maturing in a maturing cellar

Humid warehouses result in more alcohol than water evaporation, so the alcohol by volume (ABV) of the maturing cognac will steadily drop as it ages, resulting in a mellower and rounder cognac. This is typical of the house styles of Hennessy or Baron Otard/D’ussé. Typically, in humid warehouses, two to three per cent of the overall volume is lost to evaporation yearly.

Drier warehouses will result in more water being evaporated and may even result in the ABV increasing as the cognac ages. This results in a lighter, drier, spicier style. This is typical of Martell, for example. Moreover, the higher the ABV, the more compounds get extracted from the barrel wood. Typically, in a dryer warehouse four to six per cent of the overall volume is lost to evaporation each year.

Most cognac houses, including Rémy-Martin, Courvoisier and Hennessy, use a combination of humid and dryer warehouses to better manage the flavour and aroma profile of the maturing spirit. In some cases, a cellar master may move barrels to a location with more or less humidity in order to shape how the maturing spirit evolves.

Camus, for example, begins their maturation in warehouses that have a high degree of humidity and eventually moves the spirit to warehouses with lower humidity in order to create its particular house style.

Hardy also starts its barrels in humid warehouses. After two to four years, they’re moved to drier cellars for 12 to 18 months.

In Cognac, as in Scotland, most spirit is stored in humid warehouses so the ABV drops as the spirit ages.

In bourbon country, however, the opposite is true. Warehouses there are drier and the ABV often goes up as the bourbon ages. That’s one reason why you don’t find ultra-aged bourbons. A 40-year-old bourbon matured in a typical Kentucky rick house would be so woody that it would be undrinkable.

It’s rare for cognac to be matured in wood for more than 50 to 60 years. At that age, it’s usually transferred to glass demijohns where it can be stored indefinitely, without further changes, until it can be used. The demijohns along with ultra-aged barrels of cognac are typically kept in a separate area of the warehouse termed the paradis or paradise.

Although cognac was generally matured in the Cognac appellation, there were exceptions where cognac was shipped in barrels to mature elsewhere. The most common case was early shipped/late bottled (ES/LB) cognacs. These were newly distilled spirits shipped to England and matured in warehouses in London, Liverpool or Bristol.

The climate there was colder and more humid than Cognac. The resulting spirits were more delicate and refined and slightly floral. These cognacs were bottled by vintage date rather than the usual classifications. ES/LB cognacs have traditionally been associated with Hine. They are quite rare now, although older vintages still appear in auctions from time to time. ES/LB cognacs will not be permitted after 2020.

Glass demijohns of ultraaged Cognac in Hennessy’s Paradis cellar

Cognac barrels typically come in sizes of 270 to 450 litres. The 350-litre barrel is the current norm. The size of the barrel is important because the ratio of the woods surface area to the volume of liquid determines how fast the spirit matures.

A smaller barrel has a higher ratio of wood surface area to volume, so the spirit extracts more compounds from the wood and matures faster. A larger barrel has a lower ratio of wood surface area to volume and therefore matures slower.

Barrels are toasted as part of their manufacturing. Each barrel maker has their own standard for toasting or charring, typically expressed as the length of time and the temperature that the barrel wood is heated.

Cognac barrels get more toasting than barrels for wine, but far less than for barrels intended to mature bourbon or Tennessee whiskey.

There is another way of adding to the effect of traditional oak again: boise! Perfectly legal under appellation rules, boise is a liquid created by boiling oak chips. The resulting syrup-like brown substance can mimic or enhance the effect of oak aging.

Blending and bottling

The blend is at the heart of cognac and its formulation is the industry’s highest art form. This activity is the domain of the master blender or the cellar master, assisted by a committee of tasters. The master blenders at the four biggest cognac houses are responsible for the taste and mouth feel of roughly 80 per cent of the world’s cognac.

Would-be master blenders undergo a long apprenticeship before finally reaching that exalted position. In some cases, the position is passed down within the same family. At Hennessy for example, Yann Fillioux is the seventh generation of his family to hold the position of master blender.

The task of the master blender is to assemble a blend from the various mature spirits in the warehouse or cellar. Unlike many other spirits, single malt whiskies for example, which are a particular expression of a single distillery or style, cognacs achieve their sophistication and layered nuance by blending together many eau de vies.

An oft-used expression in the region is that spirit or eau de vie only becomes a cognac when it’s assembled into a harmonious blend. A cognac blend might consist of as little as a few dozen eau de vies for an entry-level VS to hundreds of eau de vies for a sophisticated, high-end XO.

The challenge of blending cognac is twofold. First, each year’s crop of spirits will be different, reflecting the vagaries of the wine from which they were produced as well as the conditions of their aging. Moreover, because the producer base is so highly fragmented, no distiller can hope to contribute more than just a very small fraction of the blend needed.

Not only must the master blender faithfully recreate the characteristic taste and aroma of a particular expression, but they have to do it from an ever-shifting array of spirit choices. In other words, for the high-volume bottlings of VS and VSOP cognacs, the master blender has to create multiple blends from different combinations of stocks that when bottled will offer the same taste and aroma profile across the entire category of cognac.

During the 19th century, the leading cognac houses all had their own systems for classifying cognac. Although there were instances of vintage dating, these were uncommon. The larger producers preferred a more open-ended system where they were free to mix and match stocks to replicate their traditional style for each type of bottling.

The current system of classifying cognacs was assembled from the marketing practices of the various houses. The term VS for very special, VSOP for very superior old pale and XO for extra old was started by Hennessy.

VSOP, for example, was specifically created by Hennessy in response to a request in 1817 by the future king George IV, for a “cognac pale.” The reference to pale meant that it was uncoloured and unsweetened. Eventually, as VSOP, it became part of the core range of cognacs.

A bottle of VSOP courvosier cognac

In the 19th century, cognac was usually sweetened to make it rounder and smoother. Today, appellation rules limit the amount of sugar to a maximum of eight grams per litre. Most houses use much less. Hennessey, for example, uses only two grams a litre of sugar in its VS and VSOP brands.

The use of one to three stars to indicate age was also originally a Hennessy marketing practice that has been retained, although the stars no longer correspond to the original age brackets.

VS carries three stars. It is the only type of cognac to still use stars on the label. The term Napoleon was first introduced by Courvoisier. The classification Extra was created by Martell to indicate, at the time, ultra-aged cognacs of 40 to 50 years.

Today, about 90 per cent of the industry’s turnover is in the VS and VSOP categories. The designation VS indicates that the youngest eau de vie in the blend is at least two years old. VSOP indicates that the youngest eau de vie in the blend is at least four years old.

In both cases, the blend is typically made of between several dozen to several hundred eau de vies. Older cognacs are included in the VS and VSOP blends, although it’s unusual to find anything older than 10 years, even in very small quantities. Remy is one exception. Their VSOP will incorporate eau de vie as old as 15 years.

XO used to indicate that the youngest eau de vie in the blend was at least six years old. The term was used interchangeably with the term Napoleon. Starting on April 1, 2018, however, the XO category moved to a minimum age of 10 years, while Napoleon will stay at the minimum age of six years.

In addition, there are a variety of other classifications. Hors d’Age means literally ageless or beyond age. Technically it has the same minimum age requirements as an XO, although most cognac houses use it to label blends of 30 YO and older cognacs.

The terms Extra and Reserve don’t have precise legal definitions. They too are used to designate blends of ultra-aged cognacs.

The term Tres Vieux, very old, is usually used to indicate a cognac house’s oldest offering, but here, too, there is no specific definition.

Ultra-premium priced, prestige bottlings get a lot of attention, especially from the media. From a financial standpoint, however, they don’t have that much impact on the bottom line.

Collectively Cognacs rated XO or higher amount for less than 10 per cent of the industry’s sales. The one exception is Rémy-Martin’s Louis XIII. Blended from around 1,200 eau de vies, it was the first ultra-premium Cognac offering and launched the category.

For many years, Louis XIII was the only ultra-premium cognac available. Historically, it outsold all of the other ultra-premium offerings combined. It’s not clear if that’s still the case.

Sales figures of ultra-premium cognac’s are a closely guarded secret, but Louis XIII is still the market leader, even though it’s possible its market share in the ultra-premium category may have now dropped below 50 per cent.

Virtually every spirit requires some blending prior to bottling. In cognac, however, the subtle influences of terroir combine with the distiller’s art and the palate of the master blender to create an extraordinary fusion of nuance and layered complexity that is an unmatched reflection of time and place.

Next week: The business of cognac.

Troy Media columnist Joseph V. Micallef is an historian, best-selling author, keynote speaker and commentator on wine and spirits. Joe holds the Diploma in Wine and Spirits and the Professional Certificate in Spirits from the Wine and Spirits Education Trust (London).